Traditional HFC systems have implemented the return path, a 5-40 MHz bandpass in North America, using bi-directional RF amplifiers in the coaxial plant, and a linear return path laser in the fiber optic node, driving a return fiber for the optical trunking. At the hub or HE, the optical power is converted back to RF. The technology is the same analog AM-based optics approach used to transport the broadcast forward path video signals. There are numerous design and implementation issues that make this approach difficult and costly, including analog laser specifications, laser second order response characteristics, optical link length constraints, optical receiver specification, and testing of the components. All of these factors contribute to the overall cost issue of developing high performance analog optics. Node laser issues are exacerbated by the fact that this component must operate in an outdoor environment, specified over a very wide temperature range.
These problems have previously been addressed with continued development in improved analog lasers and return path receiver performance, higher power lasers and modification of HFC architectures. However, each of the above-noted issues are still presented.
The present invention is therefore directed to the problem of developing a return path system that lowers the cost of return path products and improves performance such that greater architectural flexibility can be achieved, resulting in, among other possibilities increased bandwidth and capacity, and faster connection speeds to subscribers.